1. Field of the Invention
This invention relates to mold apparatus for use in the molding of customized cushion insoles for footwear, to a method of molding such insoles using such molds, and to customized cushion insoles formed using the apparatus and method.
2. Description of Prior Art
Where, as with subjects with foot deformities arising, for examples, from arthritic or diabetic conditions in the subject, customized cushion insoles are required, it is customary to make an insole for the subject using a plaster slipper on the foot, the slipper being made using a plaster bandage to form a negative mold; filling the negative mold with plaster which, when set and removed from the negative mold, gives a positive mold to the shape of the foot. An insole may, thereafter, be manufactured from any one of a variety of methods using the mold.
All such methods suffer from the following disadvantages:
(a) it is necessary to make both positive and negative molds;
an alteration to be made to an insole, for example, to relieve a pressure spot discovered after manufacture using the positive mold, must be made to the positive mold and a modified insole east therein. The success of producing a positive mold with a view to producing an insole comfortable to the wearer cannot be assured, it can be determined only by the subject for whom the insole has been prepared; the process of altering the positive mold may have to be repeated before success in relieving the discomfort of a pressure spot is achieved;
(c) plaster, by its very nature, is messy to use, requires a water supply and suitable environmental conditions and facilities, generally a special room at a hospital or clinic;
(d) the production of molds, both positive and negative, and the frequently arising requirement for modification of the positive mold to arrive at an insole satisfactory to the wearer render the process costly both as regards the facilities to be provided and as regards time spent by highly skilled personnel in the performance of the process ending with the fitting to the footwear of insoles comfortable and beneficial to the wearer.
Notwithstanding the disadvantages mentioned, procedures of the sort touched on continue as the generally accepted common practice around the world.
Mold apparatuses have been proposed which are reliant upon relative longitudinal movement between a plurality of rod elements to form a casting mold in the form of a contour which is complementary to a pattern (in some instances a human foot). Other known arrangements proposed rely on relative movement between the particles of a particulate mass. Still others rely on the formation of a depression in a suitable highly viscous fluid. Some of the prior arrangements have employed a flexible membrane as a boundary surface of the mold; others have left the mold formable body, e.g. plurality of longitudinally relatively moveable rod elements exposed.
Certain of the prior arrangements have application as a customized last or pattern from which footwear may be produced; but none of the known arrangements is suitable in the cost-effective production of customized insoles for footwear, particularly, though not exclusively, orthopaedic footwear.